Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) $ in Thousands	3 Months Ended
Mar. 28, 2020 USD ($) segment	Mar. 30, 2019 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments \| segment	1
Total net sales	$ 985,820	$ 876,718
Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 985,820	$ 876,718
Concentration percent	100.00%	100.00%
Grocery [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 863,747	$ 766,901
Concentration percent	87.60%	87.50%
Pharmacy [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 89,333	$ 81,781
Concentration percent	9.10%	9.30%
Fuel [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 29,967	$ 26,465
Concentration percent	3.00%	3.00%
Manufacturing [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,773	$ 1,571
Concentration percent	0.30%	0.20%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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